This invention relates to vane-type hydraulic motors or pumps comprising a housing, and a stator with the housing and stator defining a rotor chamber. The rotor has radially reciprocating vanes around its outer periphery and is rotatably mounted in the chamber on a shaft extending axially through the housing.
It has been found that the sharp peripheral edges of the rotor tend to gouge or bind with the sidewalls of the rotor chamber due to the pressures and shocks under which the pump or motor is operated. These gouges can also be caused by machining inaccuracies in combination with the above. To overcome this, others in the prior art have ground away or offset portions of the opposite sidewalls of the rotor to provide clearance with the sidewalls of the chamber sufficient to minimize or eliminate gouging. However, this greater clearance has enhanced oil leakage. The purpose of this invention is to overcome those problems encountered with respect to oil leakage.